Researches have been conducted to provide a multi-band, low-power, one-chip solution. A variety of wireless communication schemes have been used where each wireless communication receiver is additionally provided with a block capable of rejecting an interference signal due to other wireless communication.
A low noise amplifier (LNA) of a wireless communication receiver provides a high gain for sufficiently amplifying a weak signal input to an antenna. However, where an outband interference signal is inputted in the LNA, the linearity of the LNA's amplification may degrade. Therefore, it is desirable to eliminate an outband interference signal from a front end of the LNA.
A band pass filter (BPF) or a surface acoustic wave (SAW) filter may be used in an outband interference signal elimination method. Because it is difficult to product a high-Q (Quality factor) inductor necessary to use a sharp BPF, many wireless communication receivers use a SAW filter.
However, the use of a SAW filter may increase the implementation cost for a multi-band mode, and may cause a limitation in sharing a LNA for multi-band or multi-mode applications. Also, a SAW filter may cause an insertion loss of, for example, about 3 dB, thus degrading the RX sensitivity.